Production of elastic yarns on the woolen system



March 21, 1967 P. HERMES PRODUCTION OF ELASTIC YARNS ON THE WOOL-EN SYSTEM Filed June 1, 1964 FIG. 3.

FIG. 2.

INVENTOR. PETER I? HER/W S ATTORNEY United States Patent F 3,309,863 PRODUCTION OF ELASTIC YARNS ON THE WOOLEN SYSTEM Peter P. Hermes, Decatur, Ala., assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware Filed June 1, 1964, Ser. No. 371,657 3 Claims. (Cl. 57163) The present invention relates to the spinning of textile yarns. More particularly, this invention relates to an improved method for spinning elastic high-bulk yarns.

There are several known methods employed for making elastic high-bulk yarns. For example, an elastic strand may be twisted together with an inelastic thread or by core spinning a sheath of staple fibers about an elastic core. The twisting method comprises combining a low twist multi-filament thread with an elastic strand in an elongated condition. Core spun yarns are produced generally by introducing a continuous elastic core strand under tension between a pair of rovings of staple fibers which are helically wrapped around the core to provide a cover therefor.

In accordance with the present invention a high-bulk elastomeric yarn is'produced by a core and wrap spinning process in a single spinning operation. The core and wrap spinning process is accomplished on a conventional woolen spinning frame modified whereby a continuous elastic filament is introduced into the spinning process through the false twist tube. The elastic filament enters the false twist tube in an untwisted and elongated condition. Contact with the roping of staple fiber being spun is made within the false twist tube wherein some wrapping occurs to form a partial sheath of staple fibers around the core and the strands are subsequently twisted'together during takeup to form a composite elastomeric high-bulk yarn. Thus, the process of the present invention has the appearance of a core spinning operation initially and the core is substantially wrapped by the spun fibers during the twisting operation which occurs upon takeup of the composite yarn.

The yarn in accordance with this invention is comprised of a relatively inelastic thread. spun from an untwisted and undrawn roping of staple fibers joined with a continuous elastic filament. The inelastic thread may be any natural or synthetic textile fiber in staple form capable of being spun. Such fibers include the natural fibers cotton and wool, and the synthetic fibers nylon staple, rayon staple, polyacrylonitrile staple, polyethylene terephthalate staple, and the like. The elastic filament is a segmented elastomer in monofilament form which is comprised of segments of a high-melting polymer alternating with segments of a low melting polymer. Several suitable segmented elastomers are available. These elastomers and methods of making them are well known. Composite yarns produced in accordance with this invention may be fashioned into textile fabrics by knitting or weaving such yarns exclusively or combining them with.

other Well known yarns.

It is a primary purpose of the present invention to provide an elastic high-bulk yarn on a conventional woolen spinning system.

Another object of the present invention is to provide an improved and economical method of core and wrap spinning a high-bulk elastic yarn.

According to the present invention a high bulk elastic yarn is produced on a modified conventional woolen spinning machine at normal spinning rates. The modification consists of brackets for accommodating a spool of elastic filament having a driven roller cooperating with the spool to unwind the filament, and a pair of driven top rolls which function as holding rolls are spaced verti- Patented Mar. 21, 1967 cally above the false twist tube. The composite yarn is produced from a wool carded roping of staple fibers which is drafted and twisted together with an elastic core in a stretched condition. This process is accomplished as a normal spinning operation wherein a roping is drafted to a suitable denier inelastic thread by imparting to the roping a false twist with a tubular false twister and drawing the roping with a pair of drafting rolls. The elastic core is advanced into contact with the roping in the false twist tube and tensioned between a pair of top rolls and the drafting rolls. The amount of elongation imposed upon the elastic core is determined by the relative speed of the top rolls and the drafting rolls. The elastic core and inelastic thread become twisted together during take-up under tension to form an elastic high-bulk yarn.

Other objects and advantages of the invention will become apparent when the following detailed drawing is read in conjunction with the accompanying drawing in which FIGURE 1 is a diagrammatic view of a conventional spinning frame modified to perform the process in accordance with the invention;

FIGURE 2 illustrates a length of the yarn, greatly enlarged, in a fully extended condition; and

FIGURE 3 illustrates a length of the yarn, greatly enlarged, in a retracted condition having little or no tension imposed longitudinally on the length of yarn.

Referring now in detail to the drawings, an arrangement of apparatus for carrying out the invention is illustrated in FIGURE 1 wherein a roping It) is shown being led from a package 12 between a pair of back rolls 14 and through a false twist tube 16 to a front set of drafting rolls 18. The roping 10 is drafted into an inelastic strand of spun staple fibers in the usual manner by means of the relative speed of the front and back drafting rolls and the false twist imposed on the roping by the rotating false twist heads 19. Simultaneously, a continuous elastic filament 20 is led from a supply spool 22 between a pair of top rolls 24 aligned vertically with false twist tube 16 to prevent "contact of the filament with false twist heads 19. The elastic filament 20 is advanced through the false twist tube substantially twist free to the front drafting rolls 18 and is elongated between the top rolls 24 and front rolls 18.

The elongated filament 20 is maintained under sufiicient tension to prevent a complete wrapping thereof in the false twist tube because of the low draft condition of the spun staple fibers. However, because of the close proximity of the strands within the false twist tube some wrapping occurs to form a artial covering sheath of staple fibers spun around the elastic filament or core to join the strands together into a composite yarn 3th. The yarn 33 is advanced from drafting rolls 18 through a traveler ring 32 and taken up on bobbin 34 under tension whereby the strands 10 and 20 are twisted to produce the elastic high-bulk yarn 30 which is shown in FIG- URE 2. Thus, the yarn of this invention is produced by a combination core and wrap spinning process.

The invention can be understood more clearly by reference to FIGURES 2 and 3 in which the condition of the yarn is illustrated. As shown in FIGURE 2, the composite yarn when fully elongated is comprised of strands 10 and 2G twisted together in a ply yarn formation. Referring to FIGURE 3 it is readily apparent that the composite yarn in the absence of longitudinal tension has the appearance of a regular core spun yarn. When the elastic core is permitted to contract the staple fibers 10 bulge outwardly to form a series of helixes which provide the composite yarn with high-bulk and high retractive power. These qualities can be controlled by imposing certain limitations on the twist multiplier and the core to staple ratio as described hereafter.

The top rolls 24 are driven at a constant speed to feed the elastic filament 20 into the zone between the top rolls and the front rolls 18 at a constant speed. The zone between rolls 24 and 18 is referred to as the stretch or elongation zone since elastic filament 20 is stretched or elongated between said rolls. The amount of stretch or elongation imparted to the elastic filament 20 is a function of the speeds at which the same enters the stretch zone at the top rolls 24 and leaves this zone at the front rolls 18. Thus, the elongation ratio of the elastic filament is a function of the relative speed of the said rolls.

The following equation defines the relationship of elongation and filament speeds:

where e is the ratio of elongation length to relaxed length; S is the linear speed of the elastic filament 20 at the top ro-lls 24; and, S is the linear speed of filament 20 at the front rolls 18.

The value of e may vary from about 1.25 to 8.0 times the relaxed length of the elastic filament. For example, a one inch length of the elastic filament in its relaxed condition may be elongated from about 1.25 inches to about 8 inches. Thus,

However, the preferred range of elongation is from 2 to times the relaxed length thereof, or as represented by the equation in which By selecting the proper gearing for driving the top and front rolls 24 and 18 respectively, the speeds S and S can be changed to achieve the desired stretch or elongation of the elastic filament 20. Since the top and front rolls are gear driven from a common drive (not shown), the speeds, S and S do not fluctuate. Thus, the elongation 2 remains constant.

The amount of bulkiness and retractive power of the composite yarn is determined by the amount of twist imparted to the yarn during takeup and the elongation imposed on the elastic filament. Under a predetermined amount of twist, which is applied by the spinning frame, the degree of bulking in the composite yarn in a relaxed condition will be a function of the elongation of the elastic filament 20 as it passes through the front rolls 18. The greater the elongation of the elastic filament, also, the greater will be the bulkiness in the composite yarn in its relaxed condition provided the proper twist is put 4- into the yarn. The twist per inch may range from about 3 to 15, but preferably about 10.8 for a 3.8 run. In any event sufficient twist must be imparted to the composite yarn to prevent slippage between the strands.

A twist multiplier of about 4 or less is used. The multiplier number is determined from the formula:

Twist multiplier i 33; Inch Greater amounts of twist result in less bulking of the staple fibers when the elastic filament is in a relaxed state. The ratio of the elastic filament to the staple fibers which comprise the composite yarn is preferably about 1:2 or less by weight, but may be from 1:50 to 1:1 (2% to 50%). This process can be used to produce high-bulk elastic yarns in deniers from well below 300 to above 1000.

I claim:

1. A method of making an elastic high-bulk yarn by a combined core and wrap spinning process which comprises feeding an untwisted elastic continuous filament into a stretch zone at a constant first feed, feeding a roving of staple fibers into the stretch zone, imposing a draft on the filament and roving, imparting a false twist to the roving, forming a loosely wrapped yarn in said stretch zone by allowing the false twisted fibers to wrap about the untwisted elongated filament, withdrawing the yarn from the stretch zone at a predetermined constant second speed, and twisting the yarn together during takeup under tension to produce an elastic high-bulk yarn.

2. The method of claim 1 in which the twist multiplication of the yarn ranges from 2 to 4.

3. The method of claim 1 in which the speeds have the relationship wherein the second speed is more than 1.25 but less than 8 times greater than the first speed.

References Cited by the Examiner UNITED STATES PATENTS 647,138 10/1900 Holmes et al 57-51.4 1,254,738 1/1918 Stevens et al 57-160 2,076,270 4/1937 Harris 57-163 2,076,271 4/1937 Harris 57-163 X 2,076,273 4/1937 Harris 57-163 X 2,210,884 8/1940 Chittenden et al 57-163 2,737,773 3/1956 Clarkson 57-163 X 3,009,311 11/1961 Wang 57-152 3,038,295 6/1962 Humpheys 57-152 3,070,950 1/1963 Thomas 57-163 X 3,127,731 4/1964 McKinnon 57-152 3,166,885 l/l965 Bridgeman et al 57-152 FRANK J. COHEN, Primary Examiner.

D. E. WATKINS, Assistant Examiner. 

1. A METHOD OF MAKING AN ELASTIC HIGH-BULK YARN BY A COMBINED CORE AND WRAP SPINNING PROCESS WHICH COMPRISES FEEDING AND UNTWISTED ELASTIC CONTINUOUS FILAMENT INTO A STRETCH ZONE AT A CONSTANT FIRST FEED, FEEDING A ROVING OF STAPLE FIBERS INTO THE STRETCH ZONE, IMPOSING A DRAFT 